Multi-scale effects of agri-environment schemes on carabid beetles in intensive farmland

Agri-environment schemes (AESs) were implemented to reduce the loss of biodiversity in agro-ecosystems. This study aimed to assess whether AESs at either local or landscape scale increase the carabid abundance-activity and species richness. Carabids were sampled in 496 fields in a 430 km2 study area of central-western France. Based on the extensiveness of the agricultural practices involved, the different AES types were aggregated into three categories (AESEXT+, AESEXT++ and AESEXT+++) forming a gradient of extensiveness in farming practices. We sampled 20 fields in each of the three AESs categories. Each AES fields was paired with conventional fields. A series of statistical models were built to test the balance between the effects of AESs on either the carabid abundance-activity or species richness. AESs affected carabid abundance-activity and species richness both locally and at landscape scale (local characteristics having a greater effect than landscape composition). Carabid diversity benefited from AESs only when the most extensive practices were implemented, i.e. organic farming in cereal crops and delayed cutting in alfalfa. In addition, the local effects of organic farming and delayed cutting coverage interacted positively with these AESs at landscape scale. These results demonstrate that non-targeted organisms can benefit from AES management. They further emphasize the need to consider both local and landscape conditions when studying the effects of AESs on biodiversity. As only the most extensive practices had significant effects at both local and landscape scales, management must be planned strategically in space to ensure that AESs are distributed within the landscape to amplify their positive effects

Data from: Trait-matching and mass effect determine the functional response of herbivore communities to land use intensification

1. Trait-based approaches represent a promising way to understand how trophic interactions shape animal communities. The approach relies on the identification of the traits that mediate the linkages between adjacent trophic levels, i.e. “trait-matching”. Yet, how trait-matching explains the abundance and diversity of animal communities has been barely explored. This question may be particularly critical in the context of land use intensification, currently threatening biodiversity and associated ecosystem services. 2. We collected a large dataset on plant and grasshopper traits from communities living in 204 sampled grasslands, in an intensively managed agricultural landscape. We used a multi-trait approach to quantify the relative contributions of trait-matching and land use intensification acting at both local and landscape scales on grasshopper functional diversity. We considered two key independent functional traits: incisor strength and body size of grasshopper species. Incisor strength, a resource-acquisition trait, strongly matches grasshopper feeding niche. Body size correlates with mobility traits, and may determine grasshopper dispersal abilities. 3. Plant functional diversity positively impacted the diversity of grasshopper resource-acquisition trait, according to the trait-matching observed between plants and herbivores. However, this positive effect was significantly higher in old grasslands. In addition, the presence of specific habitats in the landscape (i.e. wood and alfalfa) strongly enhanced grasshopper resource-acquisition trait diversity in the focal grassland. Finally, body size increased with landscape simplification, although its response was modulated by local factors such as soil depth. 4. Trait-matching between plants and herbivores was an important driver explaining the abundance and diversity of resource-acquisition traits within grasshopper communities. Herbivore functional diversity in grasslands, however, cannot be understood without taking into account the presence of specific habitats in the surrounding landscape, as well as the age of the grassland. Our study suggests mass effect and assembly time are central mechanisms promoting higher functional diversity within animal communities in highly disturbed anthropogenic system

Data for Trait-matching and mass effect determine the functional response of herbivore communities to land use intensification, Le Provost, Gaëtane, Gross, Nicolas, Börger, Luca, Deraison, Hélène, Roncoroni, Marilyn, Badenhausser, Isabelle

File containing means and variances for grasshopper body size and incisor strength, local abiotic variables, local plant community variables and landscape variable

Increasing amount and quality of green infrastructures at different scales promotes biological control in agricultural landscapes

International audienceGreen infrastructures are key elements for the delivery of ecosystem services in agricultural landscapes.However, how to combine quality and quantity of green infrastructures at multiple spatial scales to optimize thedelivery of ecosystem services remains largely unknown. In this study, we investigated how hedgerow amount inthe landscape modulated the local effect of grassland quality (plant species richness) on the spillover of biologicalpest control services in adjacent sunflower fields. We quantified biological pest control and predatorcommunities in 23 adjacent sunflower-grassland field couples selected along two uncorrelated gradients: agradient of plant species richness in grassland and a gradient of hedge length in the landscape. Our study showsthat increasing the amount or the quality of green infrastructures can enhance biological pest control in adjacentcrops but that the effects depend on the pest considered. We found that weed seed predation depends only onhedge length in the large scale landscape, while aphid predation depends on plant species richness in the adjacentgrassland and on the hedge length in the immediate landscape. Also, the abundance of spiders affectsaphid predation suggesting a key role of this functional group for controlling aphids in sunflower fields. Thisstudy suggests that management options based on increasing local plant species richness should be prioritized inlandscapes with low amount of hedgerows, and confirms the fact that increasing hedgerow networks shouldpromote pest control services

Environmental variables and species traits as drivers of wild bee pollination in intensive agroecosystems—A metabarcoding approach

International audienceWild bees are known to be efficient pollinators of wild plants and cultivated crops and they are essential ecosystem service providers. However, wild bee populations have been suffering from significant declines in the last decades mainly due to the use of agrochemicals. Within this framework, we aimed to characterize wild bees' pollination spectrum (i.e., the community of pollinated flowering plants) in intensive agroecosystems, and describe the environmental variables and wild bee species traits influencing the pollination. To do this, we conducted metabarcoding analyses of pollen loads from wild bees collected in sunflower crops in the French region of Nouvelle-Aquitaine. Our study revealed that wild bees visited flowering plants corresponding to 231 different operational taxonomic units, classified into 38 families of which Asteraceae, Brassicaceae, and Apiaceae were the most visited and more than 90% of the visited taxa turned out to be wildflowers. We also analyzed the potential effect of environmental variables and wild bee species traits in governing their choice of pollinated plants. The community composition of pollinated plants varied depending on the flowering stages of the sunflower and the farming system. Our results also show that pollination niche breadth (alpha diversity) varied depending on the flowering stages of the sunflower but was not different between organic and conventional farming systems. Regarding wild bee species traits, the community composition of pollinated plants varied in relation to wild bees' body sizes and sociality levels. Our results are consistent with previous studies, suggesting that solitary bees are more specialist when it comes to flower selection than social bees, which are more generalist. The metabarcoding of pollen loads enabled us to draw a global picture of plant–wild bee interactions in an intensive agroecosystem. Our findings support the hypothesis that a higher diversity of weeds may increase wild bee diversity in intensive agroecosystem

One Year of Grassland Vegetation Dynamics in two Sheep-Grazed Agrivoltaic Systems

In agrivoltaic systems with solar fixed panels, the provision of ecosystem services by agricultural productions could be compromised due to very large changes in plant microclimate. But we still do not know properly the changes in grasslands ecosystem services. On two sheep-grazed sites located in lowland (Braize, Br) and upland (Marmanhac, Ma) grasslands of central France, we studied for one year the direct effects of various shading conditions induced by solar fixed panels on abiotic variables (light, water and soil temperature) and on vegetation (daily growth height, forage quantity and quality, number of species). Under exclosure of grazing, three treatments per site were set up, control (without solar-panel influence), inter-rows (variable influence) and panel (full influence). The results showed that light was reduced by 93% on average over the year in the shade of the panels with a cooler soil temperature of 2.6°C on Ma and 3.4°C on Br compared to the control. However, the soil moisture response varied between sites, depending on the different seasonal rainfall events and on soil texture. This resulted in 2.6 (Ma) to 3.2 (Br) times faster daily height growth and better forage quality. However, annual biomass production and species number showed no difference between the control and the panel. Only the inter-row treatment, which receives variable shading conditions throughout the day and seasons, shows variable biomass responses across sites. Experimental work will continue for several years in order to parameterise models to simulate the ecosystem services of agrivoltaic parks over the long term

Grassland-to-crop conversion in agricultural landscapes has lasting impact on the trait diversity of bees

International audienceContextGlobal pollinator decline has motivated much research to understand the underlying mechanisms. Among the multiple pressures threatening pollinators, habitat loss has been suggested as a key-contributing factor. While habitat destruction is often associated with immediate negative impacts, pollinators can also exhibit delayed responses over time.ObjectivesWe used a trait-based approach to investigate how past and current land use at both local and landscape levels impact plant and wild bee communities in grasslands through a functional lens.MethodsWe measured flower and bee morphological traits that mediate plant–bee trophic linkage in 66 grasslands. Using an extensive database of 20 years of land-use records, we tested the legacy effects of the landscape-level conversion of grassland to crop on flower and bee trait diversity.ResultsLand-use history was a strong driver of flower and bee trait diversity in grasslands. Particularly, bee trait diversity was lower in landscapes where much of the land was converted from grassland to crop long ago. Bee trait diversity was also strongly driven by plant trait diversity computed with flower traits. However, this relationship was not observed in landscapes with a long history of grassland-to-crop conversion. The effects of land-use history on bee communities were as strong as those of current land use, such as grassland or mass-flowering crop cover in the landscape.ConclusionsHabitat loss that occurred long ago in agricultural landscapes alters the relationship between plants and bees over time. The retention of permanent grassland sanctuaries within intensive agricultural landscapes can offset bee decline

Experimental assessment of insect pollination on rapeseed yield and oil quality in farmer’s field demonstrates positive effect of pollinator richness

EAGESTAD DOCT INRAPollination is an ecosystem service on which humans depends through its link to food production. Some crops, e.g. oilseed rape (Brassica napus L.), are pollinated by a broad range of insects such as by honeybees, wild bees, and hoverflies. According to experimental studies, oilseeds rape production can be increased by 10-50% by insect pollination, however these results are often obtained by comparison between presence-absence of pollinators not with pollinators gradients. Moreover, no study has investigated the effect of pollinators on the oil’s fatty acid composition while rapeseed is cultivated for oil. Here, we quantified the contribution of insect pollination on rapeseed production in terms of yield and oil quality in real farmers’ fields. We selected 352 rapeseeds plants into 73 fields in 3 consecutive years along a gradient of landscape to investigated effect of pollinators on yield and oil seed composition. In addition, 93 fields are followed by farmer’s survey to confirm effect of pollinators at field level. On each plant, we quantified total seed mass and oil composition on one control branch and one branch where pollinators were excluded using bags. Comparison between these two branch permit to estimate insect contribution. Abundance and richness of pollinator’s species in landscape are quantified by pan-traps. We show insect contribution to yield is to 27% and increase with pollinators richness whatever at the plant or field level. Pollinator’s richness also increases quality of the production by decreasing saturated acid in oil. This study confirms the crucial role of pollinator’s diversity in crop production